The certifications are an indication of your capabilities. If you start with the CCNA, and see how you get on with it. It is a useful basis to then build your knowledge and see if networking is really what you want to do for a living.
Employers will see this as a useful first step, and is almost now expected of anyone working in this field (as you are already discovering).
The further qualifications, such as the Cisco CCNP, CCSP and CCDP, the Cisco specialisations, and those from other vendors, will largely depend on what jobs you are actually doing. If you do a lot with security, then that is the likely path you will go down for certification as well.
It also depends on whether you are working for an end user, or for a reseller. Working for a reseller is where your qualifications are worth someting to the employer, as these usually count towards their partner status with the manufacturer. So they usually put you on training courses, and pay for the exams (and a bonus if you are VERY lucky !).
In summary, do the CCNA forst, and then see what you are doing in you job to decide the next step.